I have installed this on all my machines.
If you have limited vision, this program will simply amaze you. It has the draggable quality of Google Maps, combined with a magnificent zoom function and it shows a MUCH bigger area of the screen that any other magnifier I've used.
It is also a presentation aid, with a draw feature that allows the presenter to circle or highlight part of the screen display, and a simple push of the "E" key erases the drawing again.
There is a screen break feature too, but it seems to be the opposite of what I would use - I want to use the pc for (say) 45 minutes and have the screen change to tell me to take a break. This feature works more like a countdown timer - the screen is replaced by a large digital display that counts down.
Price: Free review details

This is one of those programs you run across, use on an occasional basis to fix a problem, but can never remember where the program came from.
I didn't realize these was a much newer version than the one I was using, because the program did exactly what I wanted it to do and there was no need to hunt for anything else. Recommended.
Price: Free review details